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async_hooks: avoid decrementing iterator after erase #42749

Merged
merged 2 commits into from
Apr 17, 2022
Merged

async_hooks: avoid decrementing iterator after erase #42749

merged 2 commits into from
Apr 17, 2022

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dygabo
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@dygabo dygabo commented Apr 15, 2022

decrementing an iterator returned by std::vector::erase may have
undefined behaviour and should not be used. Decrementing end()
on an empty container is undefined and .erase() could leave
the container empty.

Instead, by calling vec.erase(it--) we decrement the valid iterator
before the erase operation but after being passed to the erase method.

In case of AsyncHooks::RemoveContext perform the cleanup of empty
contexts upfront using std::remove_if because the iteration gets
interrupted as soon as the context to be removed has been found.

@dygabo
async_hooks: avoid decrementing iterator after erase
8f3ce94 
decrementing an iterator returned by `std::vector::erase` may have
undefined behaviour and should not be used. Decrementing `end()`
on an empty container is undefined and `.erase()` could leave
the container empty.

Instead, by calling `vec.erase(it--)` we decrement the valid iterator
before the erase operation but after being passed to the erase method.

In case of `AsyncHooks::RemoveContext` perform the cleanup of empty
contexts upfront using `std::remove_if` because the iteration gets
interrupted as soon as the context to be removed has been found.
@nodejs-github-bot nodejs-github-bot added c++ Issues and PRs that require attention from people who are familiar with C++. needs-ci PRs that need a full CI run. labels Apr 15, 2022
Trott
Trott approved these changes Apr 15, 2022
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I imagine there's no easy way to add a test for this, but mentioning it anyway in case I'm wrong.

@Trott Trott added request-ci Add this label to start a Jenkins CI on a PR. author ready PRs that have at least one approval, no pending requests for changes, and a CI started. labels Apr 15, 2022
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dygabo commented Apr 15, 2022

I imagine there's no easy way to add a test for this, but mentioning it anyway in case I'm wrong.

I also don't think that would be easy to write since it is difficult to test undefined behaviour. It might even act differently on different stl implementations (on some even work correctly). But the new approach should not be controversial and existing tests must stay all green.

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CI: https://ci.nodejs.org/job/node-test-pull-request/43527/

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@nodejs-github-bot nodejs-github-bot merged commit 083d4c4 into nodejs:master Apr 17, 2022
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This was referenced Apr 18, 2022
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@dygabo dygabo deleted the async_hooks-fix-empty-context-removal branch April 19, 2022 04:56
This was referenced Apr 20, 2022
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xtx1130 pushed a commit to xtx1130/node that referenced this pull request Apr 25, 2022
@dygabo @xtx1130
async_hooks: avoid decrementing iterator after erase
30e293e 
decrementing an iterator returned by `std::vector::erase` may have
undefined behaviour and should not be used. Decrementing `end()`
on an empty container is undefined and `.erase()` could leave
the container empty.

Instead, by calling `vec.erase(it--)` we decrement the valid iterator
before the erase operation but after being passed to the erase method.

In case of `AsyncHooks::RemoveContext` perform the cleanup of empty
contexts upfront using `std::remove_if` because the iteration gets
interrupted as soon as the context to be removed has been found.

PR-URL: nodejs#42749
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
targos pushed a commit that referenced this pull request Apr 28, 2022
@dygabo @targos
async_hooks: avoid decrementing iterator after erase
4694f5b 
decrementing an iterator returned by `std::vector::erase` may have
undefined behaviour and should not be used. Decrementing `end()`
on an empty container is undefined and `.erase()` could leave
the container empty.

Instead, by calling `vec.erase(it--)` we decrement the valid iterator
before the erase operation but after being passed to the erase method.

In case of `AsyncHooks::RemoveContext` perform the cleanup of empty
contexts upfront using `std::remove_if` because the iteration gets
interrupted as soon as the context to be removed has been found.

PR-URL: #42749
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
@targos targos mentioned this pull request May 2, 2022
Merged
juanarbol pushed a commit that referenced this pull request May 31, 2022
@dygabo @juanarbol
async_hooks: avoid decrementing iterator after erase
a408f87 
decrementing an iterator returned by `std::vector::erase` may have
undefined behaviour and should not be used. Decrementing `end()`
on an empty container is undefined and `.erase()` could leave
the container empty.

Instead, by calling `vec.erase(it--)` we decrement the valid iterator
before the erase operation but after being passed to the erase method.

In case of `AsyncHooks::RemoveContext` perform the cleanup of empty
contexts upfront using `std::remove_if` because the iteration gets
interrupted as soon as the context to be removed has been found.

PR-URL: #42749
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
@juanarbol juanarbol mentioned this pull request May 31, 2022
Closed
danielleadams pushed a commit that referenced this pull request Jun 27, 2022
@dygabo @danielleadams
async_hooks: avoid decrementing iterator after erase
3e34e17 
decrementing an iterator returned by `std::vector::erase` may have
undefined behaviour and should not be used. Decrementing `end()`
on an empty container is undefined and `.erase()` could leave
the container empty.

Instead, by calling `vec.erase(it--)` we decrement the valid iterator
before the erase operation but after being passed to the erase method.

In case of `AsyncHooks::RemoveContext` perform the cleanup of empty
contexts upfront using `std::remove_if` because the iteration gets
interrupted as soon as the context to be removed has been found.

PR-URL: #42749
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
targos pushed a commit that referenced this pull request Jul 11, 2022
@dygabo @targos
async_hooks: avoid decrementing iterator after erase
b69396a 
decrementing an iterator returned by `std::vector::erase` may have
undefined behaviour and should not be used. Decrementing `end()`
on an empty container is undefined and `.erase()` could leave
the container empty.

Instead, by calling `vec.erase(it--)` we decrement the valid iterator
before the erase operation but after being passed to the erase method.

In case of `AsyncHooks::RemoveContext` perform the cleanup of empty
contexts upfront using `std::remove_if` because the iteration gets
interrupted as soon as the context to be removed has been found.

PR-URL: #42749
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
@targos targos mentioned this pull request Aug 3, 2022
Merged
guangwong pushed a commit to noslate-project/node that referenced this pull request Oct 10, 2022
@dygabo @guangwong
async_hooks: avoid decrementing iterator after erase
5690fe8 
decrementing an iterator returned by `std::vector::erase` may have
undefined behaviour and should not be used. Decrementing `end()`
on an empty container is undefined and `.erase()` could leave
the container empty.

Instead, by calling `vec.erase(it--)` we decrement the valid iterator
before the erase operation but after being passed to the erase method.

In case of `AsyncHooks::RemoveContext` perform the cleanup of empty
contexts upfront using `std::remove_if` because the iteration gets
interrupted as soon as the context to be removed has been found.

PR-URL: nodejs/node#42749
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
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@jasnell jasnell jasnell approved these changes

@Trott Trott Trott approved these changes

@addaleax addaleax addaleax approved these changes

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@RaisinTen RaisinTen RaisinTen approved these changes

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